Pitch mastic for flooring



Patented Nov. 3, 1953 PITCH MASTIC FOR FLOORING Colin Buist, London, England, assignor to Coalite and Chemical Products Limited, a British com- N Drawing.

Application March 18, 1948,

Serial No. 15,719

Claims priority, application Great Britain March 19, 1947 4 Claims. (01. 106-280) The invention relates to the production of pitch mastic and more particularly to the production of pitch mastic for use in the manufacture of flooring.

The use of asphalt mastic for flooring is known. A disadvantage of asphalt mastic, however, is that any fat or oil spilt on or applied to the flooring, as in polishing, has a solvent action on the asphalt. The use of high temperature pitch for the production of pitch mastic is also known, but whereas the pitch mastic produced from a high temperature distillation process when used as a flooring is resistant to fat or oil it has the disadvantage that it cannot be satisfactorily pigmented because of the high free carbon content of the high temperature pitch. Furthermore, black is a colour which does not lend itself for use in domestic dwellings and ofiices.

It is known according to British Patent No. 568,705 that to use a coal tar pitch having a low free carbon content for the production of pitch mastic flooring enables the pitch mastic to be pigmented and thus renders it suitable for use as a flooring in dwelling houses and oflices. Such flooring, moreover, is resistant to fats and oils which may be spilt thereon, or which may be applied thereto, as for example, in a polishing operation.

It is usual furthermore, in the preparation of known mastics for use as flooring, to include in the mastic a coarse aggregate, a fine aggregate and advantageously an absorbent filler together with a pigment. The process according to the invention envisages the use of such substances in the preparation of a mastic. Such substances may be added to the mastic in known quantities such as provided by the British Standard Institution in their specification for coloured pitch mastic flooring No. 1375:1945.

There is also included in the mastic a flux which can be a coal tar derivative, such as anthracene, which is a material suitable for fluxing, which enables the material to be brought to the right consistency for laying.

It is essential in the preparation and laying of such mastic to maintain the temperature as close to, but below, a critical temperature at which the flux and/or other substances which mat be included in the mastic, give off noxious, irritant or otherwise objectionable fumes which are a danger and inconvenience to the workmen laying the floor. The known mastics suffer from the disadvantage that in the use of certain coal tar oils which contain tar acid compounds, irritant fumes are given oif on heating above the critical temperature, which must be used when preparing and laying the pitch mastic. The evolution of these irritant fumes has been one of the chief disadvantages of present-day mastics.

The invention has among its objects to avoid the evolution during the preparation of the mastic or during the laying operation, of noxious or otherwise objectionable fumes at any temperature, and particularly at the working temperature, that is to say, at the temperature to which mastic must be raised to enable it to be properly laid.

According to the invention, a flux is provided for incorporation in a pitch mastic, for use in the manufacture of mastic flooring or the like, which consists of an oil of a character which, on heating, does not give off noxious or irritant fumes; such a flux may consist of an oil derived from a middle oil fraction of the tar from a low temperature coal distillation process which oil may be refined in known manner, as by washing for the removal of tar acids and bases and subsequently distilled, or may be a petroleum derivative, such as an aromatic extract of a petroleum oil which may be a mixture of the aromatic constituents of a petroleum oil removed from the oil, as for example, by a solvent extraction process, and which is compatible with coal tar products including pitch.

Such fluxes are readily adapted to be mixed with pitch without precipitation of solid matter and are free from substances such as give rise to noxious or irritant fumes when the mastic is raised to the temperature for laying.

According to the invention furthermore, in order to increase the bulk of, and otherwise to improve the mastic, at the same time rendering it less costly to manufacture, a wood filler, advantageously in the form of sawdust or the like, may be incorporated in the mastic, thus also serving to improve the heat insulation properties of the floor. The wood is of a character such that no noxious or irritant fumes are evolved when the temperature of the mastic is raised in the laying operation: thus the wood may be a hard wood which is non-resinous and has a low moisture content. Such a filler may be incorporated up to 50% by weight of the mastic.

The physical properties of a pitch and fluxing oil as derived from the middle oil fraction of the tar derived from coal submitted for carbonising or distillation at low temperatures and the binder formed by the admixture of the pitch and oil is given in Table 1 on next page:

Table 1 Coal tar Pitch flux Binder Specific gravity at 155 O./15.5 C. (60 Fl60 F.) 1.15-1.30 Softening point (R. and B.) 70 C.80 C. (158F.l76 F.) 60 C.-70 C. (140 F.-158 F.) Matter insoluble in pure toluole (max.) 5 percent 1 percent... 5 percent. Water (max. percentage by weight) 0.5.percent 0.5 percent- 0.5 percent. Distillate (max. percentage by weight). Below 300 C. 72 F. Nil Nil. Below 330 0. (626 F.) lfi percentn Below 345 0. (653 F.). i 50 percent. Phenols (max. percentage by volume of the total) .4 0.5percent Bases (max. percentage by volume of total) 0.5 percent The basis of the fluxing oil according to the invention may be a middle oil fraction of low temperature coal oil, having an approximate boiling range between 200 C. and 330 C. with a mid-point at approximately 235 C.

The middle oil fraction referred to may comprise about 38%-40% of the'crude coal oil and may have the following composition:

The physical properties of a pitch, flux and binder according to the invention when using a flux being a petroleum product, such as an extract consisting substantially of aromatic compounds obtained by the solvent extraction of a petroleum distillate and compatible with the coal tar pitch and having an initial boiling point not substantially less than 300 C., is given in Table 2 below. The use of such a flux ensures that in blending with the pitch there is no flocculation or precipitation of resins or insoluble matter or separation of an oily phase.

The use of these fluxing oils has added to the flexibility of the mastic and less likelihood of subsequent cracking.

In one example of carrying out the process of the invention in the preparation of a fluxing oil being an oil from the middle oil derived fraction of the tar produced from coal subjected to carbonisation or distillation at low temperatures, the middle oil fraction may :be refined and may be first washed with 30 Tw. NaOH in a ratio of three parts oil to five parts NaOH to remove the tar acids.

The sodium salts of the tar acids, such as sodium cresylate, are then separated from the washed oil, which may then 'be referred to as washed middle oil.

The well settled washed middle oil may then be subjected to a chemical refining process along the following lines:

(1) Washing with 3% by volume of 40% H2804.

(ii) Washing with '1 /2% by volmne of H2804.

(iii) Washing with water to remove bulk of free acid.

(iv) Washing with 30% NaOH solution to neutralise free acid.

Table 2 Value 001. (i) pitch 001. (ii) pitch Col. (iii) flux Col. (iv) binder Specific gravity at 155 C./ 1.15

15.5 C. (60 F./60 F.) v v 1.20 V Softening point (R& B) C. 0. (203 F- 70 C80 C. (158 F. 6070'C. F;158

Matter insoluble in pure tol- 35 percent 5 percent 30 percent,

uole (B.S.805A) (max.) Water content (max. percent- 0.5;perca1t.-.-.-ma"... 0.5 percent 0.5 percent 0.5 percent.

age by weight). Distillate (max. percentageby weight). 1 Below 300 C. (573 F.) 0.1 percent Ni]. Below 345 0. (653 F.)...- 2.0 percent. Closed flash point (min.) 215 C. (420 F.)

1 Pure Benzole (B.S.l35A) may be substituted except for referee tests.

With respect to the pitch numbered (i) which (v) Washing with 4% by volume of 60 is prepared by steam blowing medium soft pitch Tw. NaOH.

at a temperature not higher than 350 C. or by prolonging the passage of steam in the normal distillation of coal tar which would otherwise yield a medium soft pitch, the physical properties 65 are given in the first column of the table; and the physical properties of a pitch obtained as a residue from the distillation of tar produced as a by-product of the low temperature carbonisation of coal in the "second column. 70

Fluxes, being aromatic extracts of petroleum oils, such as are sold under the registered trademarks Dutrex and Iranol" have been found suitable in the preparation of the mastic according to the invention.

The resultant oil of the above treatment may then be vacuum distilled, the still operating under a vacuum of 28" to 29 Hg, and the operating still temperature ranging between C. at the beginning of the distillation to 225 C. at the end.

Approximately 85% of distillate is removed in this manner, the resultant residual product, having an I. B. P. over 300 C. and a mid-point'of not lower than 345 C. being the fiuxing material according to the invention for incorporation in the mastic.

It will be understood that as a result of the 75 foregoing refining treatment and distillation the fiuxing oil is substantially free from tar acids and bases.

In preparation, the mastic is thoroughly mixed to the right consistency with the soluble binder, being the fiuxed coal tar pitch, in a proportion of from -20%, at a temperature not exceeding about 160 C. (320 F.). The mixture is cast into blocks which are re-melted on the site in mechanically agitated mixers after being broken into pieces. Before laying, the mixture is raised to a temperature of about 160 C. (320 F.) and spread by hand over the floor to be covered, the foundation being cleaned and prepared beforehand in known manner. The floors on which the mastic has been laid should not be traliicked until the mastic has cooled down to the temperature of the surrounding atmosphere.

It will be understood that a floor produced with a fluxing material according to the invention is adapted to be polished with proprietory polishes which contain petroleum derivatives, without danger of the polish exerting a solvent action on the mastic, and that any oils or fats spilt on the floor may be removed without having any solvent action on the floor.

Furthermore, having regard to the nature of the fluxing oil there is no danger of irritant or noxious fumes being evolved, even where the temperature of 160 C. (320 F.) is exceeded, thus rendering much easier the laying of the floor, which in the practice hitherto known required a laying temperature as near as possible to such temperature which has heretofore been the critical temperature in the sense hereinbefore indicated but without exceeding it.

The invention is not limited to the proportions or the composition of materials described herein by way of example.

I claim:

1. A product comprising a mastic containing a coarse mineral aggregate; a fine mineral aggregate; coal tar pitch; and a fiuxing oil composed largely of aromatic hydrocarbons compatible with coal tar pitch and having an initial boiling point of approximately 300 C. and a mid-point not less than 345 C., said fluxing oil containing substantially no tar acids or bases.

2. A product comprising a mastic containing a coarse mineral aggregate, a fine mineral aggregate, a coal tar pitch containing less than 10% of free carbon and a fiuxing oil derived from an oil fraction boiling in the range 200 C.-330 C. produced during the low temperature carbonisation of coal, the fluxing oil having an initial boiling point above 300 C. and being substantially free from tar acids and from bases.

3. A mastic comprising a coarse mineral aggregate; a line mineral aggregate; coal tar pitch; and a fluxing oil which is largely composed of aromatic hydrocarbons compatible with coal tar pitch and which has an initial boiling point of approximately 300 C., said fiuxing oil containing substantially no tar acids or bases.

4. A mastic comprising a coarse mineral aggregate; a fine mineral aggregate; coal tar pitch containing not more than 10% free carbon; and a fiuxing oil derived from the middle oil fraction of the crude oil produced during the low temperature carbonization of coal, the fiuxing oil containing substantially no tar acids or bases.

COLIN BUIST.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 760,051 Amies May 17, 1904 935,572 Amies Sept. 28, 1909 2,343,735 Baskin Mar. 7, 1944 FOREIGN PATENTS Number Country Date 1,428 Great Britain of 1914 441,503 Great Britain Jan. 21, 1936 523,458 Great Britain July 15, 1940 536,564 Great Britain May 20, 1941 568,705 Great Britain Apr. 17, 1945 

2. A PRODUCT COMPRISING A MASTIC CONTAINING A COARSE MINERAL AGGREGATE, A FINE MINERAL AGGREGATE, A COAL TAR PITCH CONTAINING LESS THAN 10% OF FREE CARBON AND A FLUXING OIL DERIVED FROM AN OIL FRACTION BOILING IN THE RANGE 200* C.-330* C. PRODUCED DURING THE LOW TEMPERATURE CARBONISATION OF COAL, THE FLUXING OIL HAVING AN INITIAL BOILING POINT ABOVE 300* C. AND BEING SUBSTANTIALLY FREE FROM TAR ACIDS AND FROM BASES. 